Endoscopes comprising such bendable and controllable portions at the distal ends of their insertion tube are described in a great number of references, some of which shall be discussed in more detail below, such as DE 101 43 966 A1, DE 42 34 833 A1, EP 0 439 931 B1 and EP 1 090 581 B1.
All of these cited references show bendable portions that are each provided at the distal ends of an insertion tube of an endoscope. Said insertion tube may be rigid or flexible. However, an essential property of the bendable portion of the insertion tube is that it is controllable with regard to its bending direction, via control wires integrated in the insertion tube.
EP 1 090 581 B1 describes a bendable portion which comprises two control wires, i.e. the bendable portion is bendable only in one plane, whereas the other aforementioned references show bendable portions comprising four control wires each, allowing the bendable portion to be bent in two planes and, thus, allowing spatial bending.
All these known bendable portions consist of a plurality of connecting rings or joint rings, respectively, or, more generally speaking, of tube segments which are connected with each other via connecting means allowing them to be pivoted relative to each other, said connecting means each being respectively arranged on the faces of the tube segments.
Now, the arrangement of the connecting means on the respective faces of the individual tube segments depends on whether the bendable portion is to be bendable only in one plane, or whether it is to be spatially bendable, i.e. in two planes. If the bendable portion is to be bendable only in one plane, as represented in EP 1 090 581 B1, there are two connecting means arranged on each face, i.e. as seen in the distal and proximal directions, said connecting parts being Located opposite each other, with a circumferential offset of 180°. The pivot axes of these connecting means on the individual tube segments respectively extend, as seen in an axial direction, on a continuous surface line.
However, if the bendable portion is to be spatially bendable, the individual tube segments need to be pivotable relative to each other also in a second plane, which is staggered 90° to the first plane. This requires the connecting means which are respectively arranged on the faces of a tube segment to be offset 90° relative to each other, as is evident, for example, from EP 0 439 931 B1. In order to also allow control of this spatial bending, there are provided, of course, four control wires, which are circumferentially offset 90° relative to each other.
The connecting means are provided as lugs, which protrude from the respective faces of the tube segments and are, for example, provided with bores into which bolts are inserted which extend radially inwardly. This means that these connecting means, especially the lug-shaped protrusions, need to overlap and, therefore, are bent outwardly or inwardly from the surface of the tube segments. However, these connecting means, and also the bolts arranged therein, then protrude beyond the outer and/or inner periphery of the bendable portion, but in particular, the bolts protrude into the interior space of the bendable portion.
The control wires are thus guided inside the bendable portion, namely, as shown in DE 42 34 833 A1 and EP 1 090 581 B1, in guides which are provided on the inner surfaces of individual tube segments. In both DE 101 43 966 A1 and EP 0 439 931 B1, such guides are provided directly at the bolt heads of the connecting means protruding into the interior space, in a manner similar to eye rings.
What all these known bendable portions have in common is that they consist of tube segments and of connecting parts, which are extremely complex with regard to their production, but especially also in respect of their mounting.
As a result, there is a need for bendable portions that substantially solves the innate drawbacks and restrictions presented with these conventional concepts and designs.